The invention relates to a cylinder head, manufacturable by the die-casting method, for water-cooled internal combustion engines with an in-line cylinder arrangement, with a plurality of niche-shaped water galleries connectable to the cooling jacket of the cylinder block, connected by cross channels and by a lateral longitudinal channel with one another.
In a known die-cast cylinder head of this design (German Offenlegungsschrift No. 21 13 840), the niche-type water galleries extend into the cylinder head from various directions. A portion of the water galleries is enclosed by a flange of the intake and/or exhaust system, designed as a cover, while another part of the water galleries must be enclosed in a cumbersome manner by a plurality of individual force-fitted cover plates. The cylinder head also has a considerable water content, which results in a high operating weight, a long warm-up time, and locally small water flow rates. Furthermore, the bores for the cylinder head bolts are disposed irregularly about the combustion chambers, and additional force-fitted cover plates or plugs are required to seal the cross channels, which run crosswise through some of these bores.
The goal of the invention is to provide a cylinder head of the aforementioned type, manufacturable by the die-casting method, which permits efficient cooling of points exposed to high heat stress with a low water content, and can be manufactured in a simple and economical fashion.
This goal is achieved by the invention in that all niche-shaped water galleries of the cylinder head are deformable at the cylinder head-cylinder block interface, and are disposed essentially around combustion chambers, the upper limit of the longitudinal channel being the highest point of the water galleries and the channels, and the longitudinal channel comprising a water outlet. The design according to the invention eliminates a great many of the water galleries which must be sealed off from the outside, with a high water content. Moreover, with bored cross channels, the inlet openings need be sealed only by plugs, covers, or flanges on the intake or exhaust manifold, which does not necessitate great expense. The cross channels and longitudinal channel used to carry away the cooling water produces a pronounced cross flow of the cooling water through the cylinder head.
Indeed, a cylinder head is already known (German Offenlegungsschrift No. 27 56 006), which is provided only with water galleries in the shape of ring segments that are open only toward the cylinder head gasket side, and an elevated longitudinal channel, but in this cylinder head, no cross channels with an improved cooling action are provided, and the cooling water is essentially conducted only lengthwise through the cylinder head, so that local temperature peaks develop.
According to a disclosed, preferred embodiment of the present invention the cylinder head is provided with bores for cylinder head bolts, four of the bores are associated with each combustion chamber such that they are located roughly on a circle about its center, two adjacent combustion chambers each have two bores in common, and each two niche-shaped water chambers are located essentially on an imaginary connecting line running at right angles to the row of combustion chambers, whereby they are each adjacent to one of the bores for cylinder head bolts and at least one combustion chamber. Such an arrangement according to the invention produces good cooling of adjacent or sequential parts of the combustion chambers and cylinders, especially in internal combustion engines with extremely small distances between the cylinders, or with cylinder sleeves which are cast in one piece. According to a further feature of the disclosed, preferred embodiment the cylinder head is provided with a cross channel running between two adjacent combustion chambers and an additional cross channel which runs parallel thereto, between inlet and outlet valves of the cylinder head, and wherein a cross channel is disposed at each end of the row of combustion chambers, the cross channels are disposed diagonally with respect to the row of combustion chambers, and the water galleries, located on the imaginary connecting line, are disposed on different sides of channels and are cut accordingly from different sides through cross channels. Such a configuration permits the cross channels to be guided past bores for cylinder head bolts and favor a staggered valve arrangement with short inlet and outlet channels and a corresponding arrangement of the spark plugs. As an additional feature of the present invention the longitudinal channel of the cylinder head terminates at one end of the cylinder head with an end opening, and expands continuously toward the latter. Such a configuration permits shaping the longitudinal channel during casting. Also, according to one form of the invention the longitudinal channel runs close to and along combustion chambers with bores for spark plugs on the side of the cylinder head which is located opposite the longitudinal channel. This arrangement favors the cooling of the combustion chamber zones which are remote from the spark plugs and has a positive influence in making the combustion chamber resistant to knocking. Further, in an internal combustion engine with a cylinder head according to the present invention, a cylinder head gasket is disposed between the cylinder head and the cylinder block. The gasket comprises openings running from the water jacket of the cylinder block to the niche-shaped water galleries with the cross sections of the openings increasing with their distance from the longitudinal channel.
In the preferred embodiment the openings located on the side of the cylinder head which is opposite the longitudinal channel each have at least the same cross section as a cross channel and the openings adjacent to the longitudinal channel have a much smaller cross section, which is approximately 1/4 to 1/2 of the cross section of the aforementioned openings. The provision of such openings in the gasket supports the formation of a pronounced cross flow through the cylinder head.